As a method for artificially cultivating a mushroom, there is fungal bed cultivation. In general, the fungal bed cultivation is carried out, first, by filling a cultivation bottle with a culture medium for a fungal bed, making a hole for inoculating a solid or liquid seed culture, and sterilizing the culture medium. Then, a seed culture suitable for the culture medium for a fungal bed is inoculated thereon, followed by cultivating the seed culture and, if necessary, after subjecting to operations such as scratching fungi, sprouting from the seed culture to generate fruit bodies in the form of a bunch from a surface of the fungal bed and harvesting a mushroom in the form of a bunch.
However, currently, since mushrooms in the forms of a bunch are in the marketplace in gross, they are not novel to general consumers. Furthermore, even if a breed having superior characteristics such as taste, as compared with those of conventional breeds is developed, differentiation of the breed from conventional ones would be difficult as long as their shapes are similar. Therefore, development of a mushroom of a large size having a sufficient presence even if it has only one fruit body rather than fruit bodies in the form of a bunch has been desired.
However, cultivation of a mushroom of a large size having high commercial value with uniform quality has been difficult because a bunch of mushrooms in clumps obtained by a conventional method have uneven thicknesses of stalks and sizes of pilei.
Then, recently, methods for fungal bed cultivation of a mushroom to obtain a fruit body of a large size mushroom have been investigated. For example, a method for cultivating an eryngii mushroom, which comprises controlling sprouting by maintaining a low humidity environment of less than 75% and a high humidity environment of 75% or more at a given interval within the environmental humidity range of from 50 to 100%, whereby a primordium is grown through vanishing within 5 days sprouting water generated when forming the primordium, has been proposed (for example, Patent Documents 1 and 2).
Further, in fungal bed cultivation of a shimeji mushroom, in particular, a bunashimeji mushroom, a method for cultivating a shimeji mushroom of a large size, which comprises sprouting through an aperture of a circular shape or approximately circular shape having an effective diameter of from 5 to 30 mm provided on the top surface of a cap set on the mouth of a cultivation bottle, has been reported (for example, Patent Document 3).
Furthermore, in fungal bed cultivation of a mushroom, a method for fungal bed cultivation of a mushroom, which comprises selecting one sprout showing good growth from plural sprouts generated on the side surface or bottom portion of a hole made on a culture medium of the bed by carrying out such a sophisticated operation that all the sprouts except the selected one are removed, followed by growing the sprout to form one fruit body per hole, has been disclosed (for example, Patent Document 4).
Patent Document 1: JP 2000-209944 A
Patent Document 2: JP 2002-233239 A
Patent Document 3: JP 11-196668 A
Patent Document 4: JP 2006-115834 A